Current availability of iobenguane I 123 is limited to single doses labeled at regional radiopharmacies with variable formulations and specific activities. The objective of this Fast track phase 1/2 SBIR is to produce and perform safety testing in humans of a new diagnostic drug product formulation of iobenguane I 123. The justification for requesting Fast Track consideration is to take advantage of the synergy of developing a diagnostic version of the high specific activity iobenguane I 123 using starting materials and facilities established for the development of the therapeutic I-131 agent. The goal of this proposal is to produce and test high specific activity Ultratrace iobenguane I 123 in normal human volunteers. The low specific activity iobenguane I 123 has been shown to be useful for the detection and staging of neuroendocrine tumors in adults and children and imaging neuronal activity in the heart. The innovation in this proposal is through the use of patented solid phase technology to produce a proven diagnostic agent at extremely high specific activity to increase sensitivity and specificity and lower radiation exposure to normal organs without the pharmacologically active cold carrier compound. The FDA considers iobenguane labeled with two different isotopes of iodine [I 131 and I 123] as two distinct drugs requiring distinct regulatory applications. To meet the required quality standards for the chemistry, manufacturing and controls component of an IND application, GMP quality polymer drug precursor will be used to generate the Ultratrace diagnostic iodine- 123 agent. Analytical methods must be validated with the proposed final drug formulation to demonstrate the final drug does not interfere with tests used to define the identity, purity, and strength of the agent. The drug product solution must also be verified to be apyrogenicity and sterility before human testing can be initiated. The formulation of the final drug product will be tested for stability and bioequivalence in norepinephrine-transporter expressing cells and in animals. The required IND application will be written and submitted to the FDA and the Duke Medical Center IRB. MIP will produce clinical trial material and conduct human testing of the radioactive drug substance for safety and superiority compared to conventional iobenguane I 123 in normal healthy volunteers.